William McKinley makes a speech during the U.S. presidential elections in 1896 at an unknown location. McKinley, who became the 25th president in 1897, was the first presidential candidate to effectively tap big corporate campaign donors.
Cost: $78.2 million*
Nearly a century before big-budget campaigns became the norm, there was Republican leader William McKinley, who may have been ahead of his time when it came to political spending. Facing populist opponent William Jennings Bryan, McKinley simply outspent the Democrat in the race to become U.S. President in 1896, shuttling in thousands of voters from around the country to be wooed by the politician at his Ohio home. McKinley also paid other Republicans — like Teddy Roosevelt, his presidential successor — to spread his gospel around the U.S., a pivotal move in what turned out to be one of the closest elections in American history. Despite doling out a staggering $3.5 million (or just less than $80 million by today's numbers; five times what his opponent spent campaigning), McKinley only beat Bryan by some 600,000 votes.
* Adjusted for inflation
* Bing: Who was Canada's PM in 1896?